1. Field of the Invention
The present invention relates to a portable device for transmitting a signal.
2. Description of the Related Art
U.S. Pat. No. 7,050,292 (corresponding to JP-A-2004-153526) discloses a portable equipment that can be used for a keyless entry system. The portable equipment includes a circuit board, a button battery, and a case body for housing the circuit board and the button battery therein. The case body includes an upper case and a lower case. The circuit board has a circuit section that includes electronic elements. The circuit section is supplied with electricity from the button battery. At opening portions of the upper case, knob pieces are disposed so that switching elements disposed on the circuit board can be controlled by operating the knob pieces.
In the case body, a water-proof cover is disposed. The water-proof cover includes a thin-film cover and a ring-shaped part integrally formed at an outer peripheral portion of the thin-film cover. The ring-shaped part is held between the upper case and the lower case. The thin-film cover is disposed between the circuit board and the knob pieces.
In the above-described portable equipment, a pressing surface of the upper case and a pressing surface of the lower case that press the ring-shaped part of the water-proof cover are required to be formed with a high accuracy so as to provide a stable waterproof property of the circuit section. In addition, the upper case and the lower case are required to have a high rigidity to maintain the pressing surfaces formed with the high accuracy. Thus, a thickness of the upper case and a thickness of the lower case may increase, and thereby a dimension of the portable equipment may increase.